how to do rays trough stone fissure
The rays in that image are actually most likely diffraction spikes caused by the aperture in the lens. To simulate that, you might try using the glare node:





Note that it helps if you have a very bright light source for the glare node to pick up on. Sun lamps are pretty good for this, but won't show up in the render directly. In the above example I made a refractive plane for the sun lamp's light to pass through, allowing it to be seen by the camera.